The coagulation proteins, Factor VIII/von Willebrand Factor and Factor IX will be isoelectric focused directly in plasma. They will then be identified with 125I labeled affinity purified antibodies. Different isoelectric patterns of Factor VIII/von Willebrand Factors will be used to classify different types of von Willebrand's disease. The function of different isoelectric forms of Factor VIII/von Willebrand Factor will be determined. Similarly, isoelectric patterns of Factor IX will be used to classify different types of hemophilia B. Following their isolation, the structural and functional relationships of different Factor IX forms will be explored.